1. Field of the Invention
The present invention relates to a color printing method for an inkjet printer, and more particularly, to a color printing method for an inkjet printer by which ink is saved to print a color image.
2. Description of the Related Art
Inkjet printers generally discharge ink droplets from an ink cartridge on a recording piece of paper to form an image. The ink cartridge is mounted in a carriage moving in a perpendicular direction to a feeding direction of the recording piece of paper. In particular, in color inkjet printers for printing a color image, a mono cartridge containing black ink and a color cartridge containing a plurality of color inks other than black, e.g., cyan, magenta, and yellow inks, are mounted in the carriage. Thus, the color image is formed by mixing the inks in both cartridges.
FIG. 1 schematically shows a conventional color cartridge. Referring to FIG. 1, a color cartridge 10 includes a housing 12, which has a predetermined internal space, and a recording head 18, which is installed underneath a bottom of the housing 12 and discharges ink droplets on the recording piece of paper. The internal space of the housing 12 is partitioned into three ink chambers 16a, 16b, and 16c by two partitions 14 that are perpendicularly installed inside the housing 12. The ink chambers 16a, 16b, and 16c contain cyan, magenta, and yellow color inks 17a, 17b, and 17c, respectively. The cyan, magenta, and yellow color inks 17a, 17b, and 17c are supplied to the recording head 18 via ink paths 19a, 19b, and 19c formed in bottom partitions of the ink chambers 16a, 16b, and 16c, and then discharged from the recording head 18 onto the recording piece of paper in the form of droplets.
As shown in FIG. 1, one color cartridge 10 generally contains the three color inks 17a, 17b, and 17c. However, amounts of the color inks 17a, 17b, and 17c that are used to print the color image different according to a color configuration of the color image. Thus, any one of the three color inks 17a, 17b, and 17c may be first exhausted, and then the two remaining color inks may be sequentially exhausted. If one particular type of color ink is exhausted, the color image having the color exhausted cannot be printed. In this case, in conventional color cartridges, a warning message informing a user of the exhaustion of the particular color ink is displayed. If the user neglects the warning message and continues a printing process, the color printer uses only the remaining color inks. For example, if the yellow color ink 17c is exhausted, the color printer only uses the cyan and magenta color inks 17a and 17b. Thus, a yellow color portion of the image is not printed. If the yellow and magenta color inks 17c and 17b are exhausted, the color printer only uses the cyan color ink 17a. Thus, yellow and magenta color portions of the image are not printed.
As described above, in the conventional color cartridges, if one or two color inks of the three color inks contained in the color cartridge are exhausted, the color image having the color exhausted cannot be obtained, i.e., the color image having the same quality as the color image printed using all of the tree color inks cannot be obtained. In this case, although some of the color inks are not completely exhausted, the color cartridge has to be replaced with a new one in order to print the color image including all the image colors. In other words, in a conventional inkjet printer, if one color ink is exhausted, an exiting color cartridge has to be replaced with a new one. Thus, a period for replacing the color cartridge is relatively short. In addition, the remaining color inks cannot be used any more.